docs: Document WSL port-forwarding TCP drop fix for Next.js UI

Problem

On WSL2, the kubectl port-forward command in kagent-feast-mcp/README.md Step 7 (line 170):

kubectl -n <YOUR_NAMESPACE> port-forward service/kagent-ui 8080:8080

randomly drops TCP connections when accessed from the Windows host browser, resulting in 504 Gateway Time-out errors and React chunk loading failures. This is because WSL2's default NAT bridging does not reliably forward traffic bound to 127.0.0.1 across the VM boundary.

Fix

The command needs --address=0.0.0.0 to bind to all interfaces:

# Before (README Step 7, line 170)
kubectl -n <YOUR_NAMESPACE> port-forward service/kagent-ui 8080:8080

# After
kubectl -n <YOUR_NAMESPACE> port-forward --address=0.0.0.0 service/kagent-ui 8080:8080

Additionally, add a note in the Prerequisites or Troubleshooting section:

### WSL2 users: port-forward drops connections

If the Kagent UI loads but becomes unresponsive or shows 504 errors,
add `--address=0.0.0.0` to the port-forward command. This is a known
WSL2 NAT bridging limitation.

File

• kagent-feast-mcp/README.md:170 (Step 7) and Troubleshooting section

Context

Discovered during local Kagent PoC validation — #59 (comment)

Open kagent-feast-mcp/README.md and inspect Step 7 around line 170, along with the Troubleshooting section. Update the documented port-forward command and add the WSL2 note described in the issue. Done means the README explains the 504 and TCP-drop symptom and shows the all-interfaces command.